He may have a point though. I condensed the error down to a simpler example. Simply ASSIGNING the workbook to a closure variable produces the error: 
use strict;
use Excel::Writer::XLSX;

&func(@ARGV);
{
    my $closure_workbook;
    
    sub func {
        my $file = 'perl.xlsx';
        my $book = Excel::Writer::XLSX->new($file);
        if (@_) {
            $closure_workbook = $book;
        }
        my $worksheet = $book->add_worksheet();
        $worksheet->write(0, 0, 'Hi Excel!');
    }
}

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In reply to Re: variable scopes in Excel::Writer::XLSX by johnrcomeau
in thread variable scopes in Excel::Writer::XLSX by johnrcomeau

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